Ferromagnetism in Co doped TiO2 films grown by RF magnetron sputtering
Abstract
Structural and magnetic properties of epitaxial Co_xTi_1-xO2 films with x about 10 %, grown by RF magnetron sputtering from composite oxide targets on matching LaAlO_3(001) substrates have been investigated. The films were sputtered at a deposition rate of ∼ 0.14 Ås for a range of substrate temperatures from 300r C to 750r C, followed by UHV annealing for 1 hour at 400r C. XRD experiments determine the best quality of highly oriented anatase (001) phase in films deposited at 500-750r C. Magnetic hysteresis loops at 5K and 300K and thermoremanence measurements at 5- 365 K show ferromagnetism in all samples in the whole temperature range. Annealing leads to an increase of spontaneous moment an order of magnitude up to ∼ 0.16 μ _B/Co atom at 300 K. Both as-grown and annealed films were found to be highly resistive (>10^9 ω /square at room temperature). AFM/MFM studies demonstrate changes both in surface morphology and distribution of spontaneous magnetization in the annealed films. Possible mechanisms of the ferromagnetic behavior of such dielectric transition metal-doped oxides will be discussed.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MAR.K1120G